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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
NASA NTRS1966

Stress corrosion

This article recounts briefly some of the more critical stress-corrosion failures that have been experienced at Marshall Space Flight Center and the corrective action taken. Some of the recent stress corrosion studies are described and preliminary results tabulated. Specific problems described are the H-1 Engine LOX dome, the pneumatic line fitting sleeve problems and the more recent problem with wave springs used on MF-flared tube fittings. The use of nitric oxide in preventing stress-corrosion failures in titanium tanks is also discussed.

HIGH STRENGTH ALLOY↗
NASA NTRSDate not supplied

Pre-Demonstration Development of Controlled-Release Corrosion Inhibitors and Healing Agents as Alternatives to Hexavalent Chromium

This Limited Scope Study was directed to achieve the following objectives: (1) Scale-up of materials that can meet MIL-PRF-23377 (solvent-based primer). (2) Provide evidence of resistance to aircraft alkaline cleaners and deicing fluids. (3) Provide formulation for initial ecological and toxicity screening. (4) Submit an interim report that will provide the basis for a future ESTCP demonstration effort. The encapsulation procedure for two corrosion inhibitors was scaled up from lab scale to 2.0 kg. This scale will accommodate high volume production of coatings with encapsulated corrosion inhibitors for large surface areas during a follow on ESTCP demonstration effort. Test results provided evidence of resistance to alkaline cleaners and aircraft deicing fluids and compliance with MIL-PRF-23377. All the MIL-PRF-23377 requirements were met with the exception of the adhesion requirement, in top coated panels, and the flexibility requirement. Work on solving these two problems will be done prior to validation and demonstration of the technology. An initial ecological and toxicity screening identified several factors that were not critical to the acceptance of the encapsulated corrosion inhibitor. This new technology will lead to environmentally friendly alternatives to hexavalent chromium that will enable DoD to protect its assets. Field demonstration, licensing, qualification, and commercialization will allow its real world utilization.

Alternatives to Hexavalent Chromium, Controlled Re↗
DOE OSTI2020

Galvanic Corrosion of Carbon Steel and Stainless Steel Couples: Effects of γ-Radiation and Solution Environment - 20348

Galvanic corrosion between carbon steel (CS) and stainless steel (SS) in different aqueous environments was investigated using a combination of electrochemical measurements and surface characterizations. In a basic environment (pH 10.6), the galvanic effect is negligible due to the high corrosion resistance of both alloys. In an acidic to near neutral environment (pH 6.0), the galvanic effect is more significant. Coupling to SS, increasing temperature, and irradiation at this pH have a synergistic effect on the corrosion progression of CS, and their effects vary with time. Initially, the oxidation rate of CS increases after galvanic coupling to SS. Increasing temperature or applying γ-radiation accelerates this oxidation process. However, at a longer time when the saturation limits of metal cations are reached, they also lead to the formation and growth of oxides on CS at a much faster rate, resulting in the suppression of the subsequent Fe dissolution. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2026

Determining Drying Conditions to Mitigate Hanford Double Shell Storage Tank Underside Corrosion — Phase 1

The Hanford Site in Washington State has legacy radiological waste that is being retrieved from single shell tanks (SSTs) and transferred to newer, double shell tanks (DSTs) for eventual closure of the SSTs. The waste is maintained in the DSTs until eventual immobilization can be performed at the Waste Treatment and Immobilization Plant (WTP), currently under construction. Until full immobilization is complete, extended service of the DSTs must be ensured by mitigating corrosion of the steel tank walls and buried steel pipelines. A Pit Air Supply System has been developed to mitigate corrosion of the leak detection pits connected to the concrete foundations of the DSTs. The objectives for the present study are: (i) to corrode steel specimens in an electrolytic simulant to form artificial pits with specific pit depths, and (ii) to determine the temperature and humidity levels that will mitigate further pit growth. Experimental work and results will be presented to evaluate conditions associated with the PASS system and predict corrosion rates when the PASS is operating.

Atmospheric Corrosion↗
DOE OSTI2025

Automated Image Segmentation and Processing Pipeline Applied to X–Ray Computed Tomography Studies of Pitting Corrosion in Aluminum Wires

Understanding pitting corrosion is critical, yet its kinetics and morphology remain challenging to study from X-ray computed tomography (XCT) due to manual segmentation barriers. To address this, an automated pipeline leveraging deep learning for efficient large-scale XCT analysis is developed, revealing new corrosion insights. The pipeline enables pit segmentation, 3D reconstruction, statistical characterization, and a topological transformation for visualization. Here, the pipeline is applied to 87 648 XCT images capturing commercial purity aluminum (1100 Al) wire exposed to sodium chloride (NaCl) salt particles over a period of 122 h. The pipeline achieves complete feature extraction and statistical quantification across the entire XCT dataset, leveraging distributed computing environment for high efficiency. Global growth kinetics such as high-level stepwise sigmoidal volume loss patterns and granular individual pit developments are both captured for 36 detected pits. By combining automation, computer vision, and extensive XCT datasets, this research accelerates precise corrosion assessment to enable materials science discoveries at scale.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Effect of Oxidizing Impurities on the Corrosion Behavior of Structural Alloys Exposed to MgCl 2 Molten Salt Vapor

The corrosion behavior of structural alloys SS304 and IN617 when exposed to vapors of MgCl 2 molten salt at 764 °C for 100 h in an argon atmosphere was investigated as a function of the level of oxidizing impurities (e.g., NaOH) present in the salt. Increasing the concentration of oxidizing impurities in the salt caused an increase in corrosion in both structural alloys, as measured by Cr depletion layers. A poorly adhered oxide scale layer containing Mg, Al, and Cr was observed on the surface of the metals, and local attack was observed as well. The Ni-based IN617 showed lower Cr depletion and less scale formation than the Fe-based SS304. These results demonstrate that oxidizing impurities in the molten salt will impact the vapor phase corrosion for structural members exposed to the molten salt headspace. This finding is highly relevant for understanding the effects of the vapor phase in molten salt applications, including molten salt thermal energy storage, molten salt nuclear reactors, and molten salt electrochemistry.

25 ENERGY STORAGE↗
DOE OSTI2024

Corrosion Behavior of a Reactive Bond Between Stainless Steel and a Cast AlCeMg Alloy

Corrosion is a longstanding issue for metal components, especially those used in heat exchanger applications. Al–Ce–Mg alloys may provide a potential solution to this problem due to their good mechanical properties and potential reaction bonding with other metals. The reaction bonding involves a “reactive” bond that occurs upon casting of Al–Ce–Mg alloy over stainless steel (SS). Here this study examined the corrosion response of Al–2Ce–6Mg (atomic percent)/(SS) reactive bond interfaces after samples were completely submerged in nitric, sulfuric, formic, and mixed acids for 267 h. Scanning electron microscopy revealed that in the as-cut condition, reactive bond formations were seen frequently throughout the length of the casting and maintained a secure bond between the alloy and the SS tubes. Furthermore, the nitric, sulfuric, and the mixed acids did not have a deleterious effect on the reactive bond structure. However, formic acid did produce changes in both the microstructural appearance and the elemental profile across the bond due to the formation of corrosion reaction products on the acid-exposed surface.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Morphologies of dealloying corrosion attack at grain boundaries

Dealloying corrosion at grain boundaries severely compromises the performance of polycrystalline materials across a wide variety of technological applications. The impact of this phenomenon depends upon the morphology and rate of intergranular dealloying, which can range from planar to wormhole-like patterns that rapidly advance into the alloy. Using 2D and 3D multi-phase field simulations, we reveal how diverse microstructures result from a fundamental interplay between alloy composition and a grain boundary migration mechanism that alters diffusional pathways of dealloying. Inside intergranular dealloying channels, corrosion product buildup can spawn new channels that branch into grain interiors, such that alloys can be degraded from the inside out. These processes further lead to an atypical coarsening mode assisted by diffusion in the dealloying agent. We summarize a unifying explanation for dealloying morphology selection in polycrystalline alloys, which provides an important step towards their optimization for dealloying corrosion environments.

Corrosion↗
DOE OSTI2020

Investigation of impurity driven corrosion behavior in molten 2LiF-BeF 2 salt

A 1000 -h corrosion experiment of 316H stainless steel at 700 °C investigated the role of metal fluoride impurities CrF 2 and FeF 2 in LiF-BeF 2 (66-34 mole %) (FLiBe) salt. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) demonstrated the ability to measure changes in the concentration of these fluorides in FLiBe salt. Cyclic voltammetry (CV) showed the potential for real-time quantitative concentration measurement of corrosion products in the molten salt. Materials characterization revealed that both impurity species influence the dissolution of Cr from the alloy. The collective results from these analysis methods advance the understanding of the influence impurities have on materials corrosion.

2LiF-BeF2↗
DOE OSTI2020

Non-galvanic mass transport in molten fluoride salt isothermal corrosion cells

Mass transport of corrosion products between Ni-201 test samples and 316 L capsules in a 500-hour FLiNaK corrosion experiment has been investigated. In one experiment, the capsule and samples were electrically connected for galvanic coupling, while in the other they were electrically isolated using boron-nitride. Post-corrosion characterization of Ni-201 from the two experiments did not reveal any remarkable differences. Substantial transport of Fe and Cr from the 316 L to the Ni-201 via the salt was observed, with notable diffusion of these elements in the near-surface regions of the Ni-201 samples, while a Cr-rich film was also observed on their surfaces.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Comparison of Na 2 SO 4 , K 2 SO 4 and Na 2 SO 4 -K 2 SO 4 deposit induced hot corrosion of a β-NiAl coating

Here, hot corrosion behaviour of a β-NiAl coating induced by Na 2 SO 4 , K 2 SO 4 , and Na 2 SO 4 -K 2 SO 4 deposits was investigated at 700 °C in air + 300 ppm SO 2 . To provide an insight into the corrosion mechanisms, phase equilibria of the Na 2 SO 4 -K 2 SO 4 -NiO-SO 3 system were calculated using an in-house developed thermodynamic database. The attack rates and morphologies could be correlated with the deposit compositions and their reactions with oxides. K 2 SO 4 and Na 2 SO 4 -K 2 SO 4 deposits are more corrosive than Na 2 SO 4 . This is attributed to a reduction of the melting temperature of the deposit and the formation of Ni-containing mixed sulphate phases in the presence of K 2 SO 4 .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Effect of metal fluorides on the corrosion of structural materials in molten LiF-NaF-KF

The corrosion of structural materials in molten fluoride salts is predominantly caused by the presence of impurities in the salt. Here, this study focuses on understanding the corrosion behavior of selected alloys in molten FLiNaK salt with addition of similar quantities of metal fluoride impurities such as CrF 2 , CrF 3 , FeF 2 , FeF 3 , and NiF 2 . The results show that the presence of selected metal fluoride impurities increases the extent of corrosion of the selected alloys in molten FLiNaK salt, with the exact effect depending on the thermodynamic stability of the fluoride impurity added as well as the composition of the structural alloy studied.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Influence of native oxide film on corrosion behavior of additively manufactured stainless steel 316L

The influence of the native oxide film on passive film properties and localized corrosion of additively manufactured SS 316L was studied in 1 wt% HCl by XPS characterization, electrochemical polarization curves, and post-test morphology analysis by SEM. Increased Cr oxidation kinetics was observed in the as-polished sample with the native oxide film resulting in formation of an overall more protective and compact film compared to the cathodically-activated sample. Electrochemical analysis showed that corrosive attack varied between dislocation cell boundaries to cell interiors depending on the initial surface state and polarization conditions. In conclusion, a corrosion mechanism is proposed to explain this variation.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Corrosion characteristics of silicon carbide fiber-reinforced composites in beryllium-bearing molten fluoride salt

Corrosion of SiC-fiber reinforced SiC matrix composites in 2LiF-BeF 2 molten salt was examined following static molten salt exposure for 1000 h at 650 and 750 °C. Composites were fabricated with either Tyranno SA3 or Hi-Nicalon type-S fibers and a chemical vapor infiltration SiC matrix. Both composites showed minimal weight loss after salt exposure and maintained shape. Corrosion was characterized by comprehensive electron microscopy and Raman spectroscopy. In conclusion, based on the results of experimental and thermodynamic analysis, a corrosion mechanism for SiC/SiC is proposed where both the salt and SiC materials play a key role in the phase stability of the composite.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Localized Corrosion Behavior of Non-Equiatomic NiFeCrMnCo Multi-Principal Element Alloys

A series of single phase Ni 38 Fe 20 Cr x Mn 21–0.5x Co 21–0.5x multi-principal element alloys (MPEAs) were fabricated and their localized corrosion behavior was tested in 0.6 M NaCl solution. These MPEAs were found to be susceptible to localized corrosion, exhibiting pitting at room temperature, as indicated by positive hysteresis loops and low repassivation potentials observed in cyclic potentiodynamic polarization experiments. The pitting resistance increased with increasing Cr content. Interestingly, even the MPEAs with low chromium content, Ni 38 Fe 20 Cr 6 Mn 18 Co 18 and Ni 38 Fe 20 Cr 10 Mn 16 Co 16 , exhibited passivity and localized corrosion. Here, the passivity observed in these low chromium MPEAs is likely derived from their relatively high nickel content. Crystallographic pit morphology was observed in most of these MPEAs, suggesting the absence of a salt film on the dissolving pit surface. Such crystallographic pit morphology indicates that the pit growth in most of these MPEAs was under charge-transfer/ohmic control.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Niobium addition improves the corrosion resistance of TiHfZrNb x high-entropy alloys in Hanks’ solution

High-strength TiHfZrNb x high-entropy alloys could become the ideal materials for small-diameter endovascular stents once their corrosion resistance in the physiological milieu is confirmed. Here, this work aims at evaluating the corrosion resistance of a TiHfZrNb x high-entropy-alloys family in Hanks’ solution at 37 °C and revealing the influence of niobium on the mechanisms of dissolution and passivation. The alloys were subjected to a series of static and dynamic electrochemical tests and surface characterization, employing the static/dynamic/cyclic polarizations, impedance spectroscopy, XPS, AFM, and SEM. Results confirm a higher corrosion resistance of the alloys compared to that of CP-Ti and Ti6Al4V. The addition of niobium considerably improves the microstructural homogeneity that ensures a low dissolution rate and a greater resistance of the film due to the lower concentration of point defects. The passive film behaves as an n-type semiconductor and is composed of a mixture of TiO 2 , Nb 2 O 5 , ZrO 2 , and HfO 2 oxides, with the presence of metallic hydroxides on the outermost layer. A detailed description of the niobium influence on the mechanisms of the dissolution and passivation is presented in this work.

36 MATERIALS SCIENCE↗
DOE OSTI2025

A methodology for corrosion testing ODS steels in liquid tin under reactor conditions in HFIR

Liquid metal–based divertor concepts have promising attributes for application in fusion reactors. Liquid tin is being considered as one of those liquid metals due to its excellent thermophysical properties. However, tin is extremely corrosive to steels at elevated temperatures, and the coupled effects of corrosion with neutron irradiation for application in fusion reactors have not been quantified. Researchers at Oak Ridge National Laboratory (ORNL) have designed and irradiated a series of capsules in the High Flux Isotope Reactor (HFIR) to help address gaps in the literature with respect to coupled corrosion and neutron irradiation effects. The capsules are filled with solid tin designed to melt due to the gamma heating in HFIR and allow interaction with the specimens. The capsules contain a SiC thermometer for post-irradiation temperature verification. Five capsules were irradiated in HFIR for 10.5 days, accumulating 0.93 dpa in the FeCrAl specimens. Post-irradiation temperature verification was performed on the SiC thermometers, and temperatures were observed to be higher than what was expected from thermal models. An explanation for the model underprediction is given herein. In conclusion, the capsules described within this article are the first to irradiate liquid metal within the HFIR flux trap and demonstrated the safety basis for continued liquid coolant studies in HFIR.

FeCrAl↗
DOE OSTI2021

Hydroxide melt induced corrosion of Ni at elevated temperatures under steam electrolysis conditions

Molten alkali electrolyte based high temperature water electrolysis (HTWE) process offers an efficient pathway to integrate renewable energy resources for large scale and economic hydrogen production. Long term and stable operation of these systems require an in-depth understanding of materials stability under anodic and cathodic exposure conditions of the cell and cell stacks. In the present study, we report our findings on the corrosion of Ni in the presence and absence of (LieNa) hydroxide melt at 600 °C under oxidizing and reducing conditions representative of HTWE. While the Ni electrode was found to remain thermodynamically stable in metallic form under cathodic (reducing) exposure conditions, the corrosion rate in molten hydroxide under oxidizing conditions was found to be nonparabolic in nature. A cyclic voltammetry study provides the breakdown of the passive metal-oxide surface layer at the anodic overpotential region between 0.45 V and 2 V in molten hydroxide under oxidizing conditions. As a result, a thermochemical process for accelerated corrosion based on the oxide scale fluxing in hydroxide melt has been developed.

08 HYDROGEN↗